I'd be really leary about the sand. though I'm not an expert, you would think there would be a lot of dead stuff in it from sitting in a bag (assuming you bought bagged live sand) all that time.
I've set up new tanks from existing rock but always used sand from the same existing tank. There's a fine line between it being considered a tank transfer, and a new setup. You might be skirting the wrong side of that line.
But as others have said, take it slow, some things are going to have to run their course, don't go crazy on the WC's but don't outright stop them either. Test your params as often as you deem useful and good luck
